. ♪ no one to save you but yourself ♪ >> reporter: troian belisario who plays alpha spencer, has been. but boy, have times changed since selleck's mustache ruled the air waves. >> being on social media is very much a part of my job. >> part of your job. >> yes, it is part of my job. >> do you guys respond to the feedback on social media? and does that then shape where you take the show? >> oh, immensely. >> hanna! watch out. >> reporter: they delve deeper into mysteries. >> you're too much. >> reporter: created even higher cliff-hangers. because fans ask for it. >> it is a giant test group of millions of fans every night. >> reporter: pll is about to kick off its fifth season on abc family. so what's it actually about? >> well, i think that it plays on a very important piece of adolescent psychology, which is that when you are this age it feels like the world is revolving around you. people either hate you or they love you. we're actually the manifestation of those insecurities. >> they did warn me that you were the smart one. >> sorry. we also have lots of hot guys with abs. does tha